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Arsenic release from paddy soils during monsoon flooding

Source: Nature, Date: December , 2009

Bangladesh relies heavily on groundwater for the irrigation of dry-season rice. However, the groundwater used for irrigation often contains high concentrations of arsenic. In seasonally flooded fields, topsoil arsenic concentrations decrease during the monsoon season, suggesting that flooding attenuates arsenic accumulation in the soils.In a test conducted by a group of scientists from Switzerland, Bangladeshand Germany ,arsenic was distributed throughout the entire floodwater column by vertical mixing and was laterally removed when the floodwater receded. They have come to the conclusion that monsoon floodwater removes a large amount of the arsenic added to paddy soils through irrigation, and suggest that non-flooded soils are particularly at risk of arsenic accumulation.